An accurate determination of the heats of combustion of various hydrocarbons is necessary in a variety of applications. For example, the production of simulated test media in wind tunnels for hypersonic vehicle studies requires a knowledge of the hydrocarbon properties. Also, natural gas suppliers often mix gas supplies from different sources. Since these mixtures must meet minimum federally mandated Btu standards, a determination of the heat of combustion for the mixture is necessary. Currently, this determination occurs off-line in a laboratory.
Several methods are currently utilized to determine the heats of combustion for gaseous hydrocarbons. One method, known as water-flow calorimetry, transfers heat resulting from hydrocarbon combustion to water and then measures the resulting temperature rise of the water, which is proportional to the heat of combusion. Disadvantages of water-flow calorimetry include a lengthy response time due to the relatively high thermal resistance of water and inexact data due to heat losses to the surrounding environment. Another method involves catalytically burning air and hydrocarbon gas of known volumetric flow-rates and then measuring the amount of oxygen utilized by combustion. This measured amount of oxygen is proportional to the heat of combustion of the hydrocarbon gas. One disadvantage of this method is that some prior knowledge of the hydrocarbon gas is needed. First, the air used must have sufficient oxygenic content to completely oxidize the hydrocarbon gas, which necessitates some knowledge of the composition of the hydrocarbon gas. Second, some knowledge of the composition of the hydrocarbon gas is required to select the optimal catalyst.
Accordingly, it is an object of this invention to provide an accurate method and device for measuring the heats of combustion of hydrocarbon gases which requires no prior knowledge of the hydrogen gas.
It is a further object of this invention to provide an accurate method and device for measuring the heats of combustion of hydrocarbon gases which may be quickly performed.
It is a further object of this invention to provide an accurate method and device for measuring the heats of combustion of hydrocarbon gases which may be performed on-line.
It is a further object of this invention to provide an accurate method and device for measuring the heats of combustion of hydrocarbon gases which can also be used for a mixture of hydrocarbon gas and inert gases such as nitrogen and helium.
Other objects and advantages of this invention will become apparent hereinafter in the specification and drawings which follow.